coresight: etm4x: Drop the useless tweak of TRCIDR1

The TRCIDR1 fall back check is problematic and has been removed by
commit 97302eb6 ("coresight: etm4x: Do not access TRCIDR1 for
identification"), so the tweak of TRCIDR1 introduced by commit
233b9a7d ("coresight: etm4x: Add support for Marvell OcteonTX2")
also become useless, let's drop it too.

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>